The Validation of Ground Bit Setting

As a block of the surveillance system thread in the aviation system block upgrade, the DAPs (downlink aircraft parameters) application is currently being implemented in country around the world. China has been accelerating this application in automated traffic management operation. During the implementation, it was noticed that the data from transponder were not always correct. It is required that validate the data to guarantee the data correct. Most of the DAPs data are stored in different binary data storages registers. These data must be extracted with known interrogation. The validation of them needs extra interrogation, and it might bring over interrogating and negative impact on the air traffic management. GBS (Ground Bit Setting) is a bit indicates whether the aircraft is on the ground. It can be extracted without extra interrogation, because it can be extracted from ADS-B (Automatic Dependent Surveillance-Broadcast) message and responding message to unknown interrogation by other interrogator. So the validation of it would not have negative impact. A method was proposed to validate GBS, and with this method, two aircraft with erroneous GBS reporting was found in record data. In future, it was hoped to extend the validation to the DAPs data which were extracted with known interrogation.